Method for performing communication in wireless lan system, and wireless terminal using same

ABSTRACT

Disclosed is a method for communicating in a wireless LAN system performed by a first wireless terminal, the method including: generating a wake-up packet modulated by an On-Off Keying (OOK) technique wherein the wake-up packet comprises a plurality of identification information for a plurality of second wireless terminals, each of the plurality of identification information is generated based on a bit length unit having a fixed size, and the bit length unit having the fixed size is set to 12 bits; and transmitting the wakeup packet to the plurality of second wireless terminals.

TECHNICAL FIELD

The present disclosure relates to wireless communication, and moreparticularly, to a method for communicating in a wireless LAN system anda wireless terminal using the same.

BACKGROUND ART

Discussion for a next-generation wireless local area network (WLAN) isin progress. In the next-generation WLAN, an object is to 1) improve aninstitute of electronic and electronics engineers (IEEE) 802.11 physical(PHY) layer and a medium access control (MAC) layer in bands of 2.4 GHzand 5 GHz, 2) increase spectrum efficiency and area throughput, 3)improve performance in actual indoor and outdoor environments such as anenvironment in which an interference source exists, a denseheterogeneous network environment, and an environment in which a highuser load exists, and the like.

An environment which is primarily considered in the next-generation WLANis a dense environment in which access points (APs) and stations (STAs)are a lot and under the dense environment, improvement of the spectrumefficiency and the area throughput is discussed. Further, in thenext-generation WLAN, in addition to the indoor environment, in theoutdoor environment which is not considerably considered in the existingWLAN, substantial performance improvement is concerned.

In detail, scenarios such as wireless office, smart home, stadium,Hotspot, and building/apartment are largely concerned in thenext-generation WLAN and discussion about improvement of systemperformance in a dense environment in which the APs and the STAs are alot is performed based on the corresponding scenarios.

DISCLOSURE Technical Problem

An object of the present disclosure is to provide a method forcommunicating in a wireless LAN system having improved performance interms of overhead and a wireless terminal using the same.

Technical Solution

According to an aspect of the present disclosure, there is providedmethod for communicating in a wireless LAN system performed by a firstwireless terminal, the method including: generating a wake-up packetmodulated by an On-Off Keying (OOK) technique wherein the wake-up packetcomprises a plurality of identification information fields for aplurality of second wireless terminals, each of the plurality ofidentification information fields is generated based on a bit lengthunit having a fixed size, and the bit length unit having the fixed sizeis set to 12 bits; and transmitting the wakeup packet to the pluralityof second wireless terminals.

Advantageous Effects

According to an embodiment of the present disclosure, a method forcommunicating in a wireless LAN system having improved performance and awireless terminal using the same are provided.

DESCRIPTION OF DRAWINGS

FIG. 1 is a conceptual diagram illustrating a structure of a WLANsystem.

FIG. 2 is a diagram illustrating an example of a PPDU used in an IEEEstandard.

FIG. 3 is a conceptual view illustrating an authentication andassociation procedure after scanning of an AP and an STA.

FIG. 4 is an internal block diagram of a wireless terminal receiving awake-up packet.

FIG. 5 is a conceptual diagram illustrating a method in which a wirelessterminal receives a wake-up packet and a data packet.

FIG. 6 illustrates an example of a WUR PPDU format.

FIG. 7 illustrates a signal waveform of a wake-up packet.

FIG. 8 is a diagram illustrating afrequency-division-multiplexing-access (FDMA) based WUR PPDU having a 40MHz channel bandwidth.

FIG. 9 is a diagram illustrating a design process of a pulse accordingto OOK.

FIG. 10 illustrates a basic operation for a WUR STA.

FIG. 11 is a diagram illustrating a MAC frame structure for a WUR frameaccording to an embodiment.

FIG. 12 is a diagram illustrating a structure of a frame control fieldof a WUR frame according to an embodiment.

FIG. 13 is a flowchart illustrating a method for communicating in awireless LAN system according to an exemplary embodiment from an APperspective.

FIG. 14 is a flowchart illustrating a method for communicating in a WLANsystem according to an exemplary embodiment from a STA perspective.

FIGS. 15 to 21 illustrate a format structure of a VL WUR frame includinga plurality of identification information fields configured based on abit length unit having a variable length.

FIG. 22 is a diagram of a method of determining information on a size ofidentification information fields for a wireless terminal according toanother embodiment.

FIGS. 23 and 24 illustrate a format structure of a VL WUR framedepending on a transmission rate according to yet another embodiment ofthe present disclosure.

FIG. 25 is a block diagram illustrating a wireless device to which thepresent embodiment is applicable.

MODE FOR DISCLOSURE

The above-described features and the following detailed description areexemplary contents for helping a description and understanding of thepresent specification. That is, the present specification is not limitedto this embodiment and may be embodied in other forms. The followingembodiments are merely examples to fully disclose the presentspecification, and are descriptions to transfer the presentspecification to those skilled in the art. Therefore, when there areseveral methods for implementing components of the presentspecification, it is necessary to clarify that the present specificationmay be implemented with a specific one of these methods or equivalentthereof.

In the present specification, when there is a description in which aconfiguration includes specific elements, or when there is a descriptionin which a process includes specific steps, it means that other elementsor other steps may be further included. That is, the terms used in thepresent specification are only for describing specific embodiments andare not intended to limit the concept of the present specification.Furthermore, the examples described to aid the understanding of thepresent specification also include complementary embodiments thereof.

The terms used in the present specification have the meaning commonlyunderstood by one of ordinary skill in the art to which the presentspecification belongs. Terms commonly used should be interpreted in aconsistent sense in the context of the present specification. Further,terms used in the present specification should not be interpreted in anidealistic or formal sense unless the meaning is clearly defined.Hereinafter, embodiments of the present specification will be describedwith reference to the accompanying drawings.

FIG. 1 is a conceptual diagram illustrating a structure of a WLANsystem. FIG. 1(A) illustrates a structure of an infrastructure networkof institute of electrical and electronic engineers (IEEE) 802.11.

Referring to FIG. 1(A), a WLAN system 10 of FIG. 1(A) may include atleast one basic service set (hereinafter, referred to as ‘BSS’) 100 and105. The BSS is a set of access points (hereinafter, APs) and stations(hereinafter, STAs) that can successfully synchronize and communicatewith each other and is not a concept indicating a specific area.

For example, a first BSS 100 may include a first AP 110 and one firstSTA 100-1. A second BSS 105 may include a second AP 130 and one or moreSTAs 105-1 and 105-2.

The infrastructure BSSs 100 and 105 may include at least one STA, APs110 and 130 for providing a distribution service, and a distributionsystem (DS) 120 for connecting a plurality of APs.

The DS 120 may connect a plurality of BSSs 100 and 105 to implement anextended service set (hereinafter, ‘ESS’) 140. The ESS 140 may be usedas a term indicating one network to which at least one AP 110 and 130 isconnected through the DS 120. At least one AP included in one ESS 140may have the same service set identification (hereinafter, SSID).

A portal 150 may serve as a bridge for connecting a WLAN network (IEEE802.11) with another network (e.g., 802.X).

In a WLAN having a structure as illustrated in FIG. 1(A), a networkbetween the APs 110 and 130 and a network between APs 110 and 130 andSTAs 100-1, 105-1, and 105-2 may be implemented.

FIG. 1(B) is a conceptual diagram illustrating an independent BSS.Referring to FIG. 1(B), a WLAN system 15 of FIG. 1(B) may performcommunication by setting a network between STAs without the APs 110 and130, unlike FIG. 1(A). A network that performs communication by settinga network even between STAs without the APs 110 and 130 is defined to anad-hoc network or an independent basic service set (hereinafter, ‘BSS’).

Referring to FIG. 1(B), an IBSS 15 is a BSS operating in an ad-hoc mode.Because the IBSS does not include an AP, there is no centralizedmanagement entity. Therefore, in the IBSS 15, STAs 150-1, 150-2, 150-3,155-4, and 155-5 are managed in a distributed manner.

All STAs 150-1, 150-2, 150-3, 155-4, and 155-5 of the IBSS may beconfigured with mobile STAs, and access to a distributed system is notallowed. All STAs of the IBSS form a self-contained network.

The STA described in the present specification is a random functionmedium including a medium access control (hereinafter, MAC) following astandard of the Institute of Electrical and Electronics Engineers (IEEE)802.11 standard and a physical layer interface for a wireless medium andmay broadly be used as a meaning including both an AP and a non-APstation (STA).

The STA described in the present specification may also be referred toas various names such as a mobile terminal, a wireless device, awireless transmit/receive unit (WTRU), a user equipment (UE), a mobilestation (MS), a mobile subscriber unit, or simply a user.

FIG. 2 is a diagram illustrating an example of a PPDU used in an IEEEstandard.

As illustrated in FIG. 2, various types of PHY protocol data units(PPDUs) may be used in a standard such as IEEE a/g/n/ac, etc. In detail,LTF and STF fields include a training signal, SIG-A and SIG-B includecontrol information for a receiving station, and a data field includesuser data corresponding to a PSDU.

The present embodiment proposes an improved scheme for a signal (orcontrol information field) used for a data field of a PPDU. The signalmentioned in the present embodiment may be applied onto high efficiencyPPDU (HE PPDU) according to an IEEE 802.11ax standard. The signalmentioned in the present specification may be HE-SIG-A and/or HE-SIG-Bincluded in the HE PPDU. For example, the HE-SIG-A and the HE-SIG-B mayalso be respectively represented as SIG-A and SIG-B. However, the signalmentioned in the present specification is not necessarily limited to anHE-SIG-A and/or HE-SIG-B standard and may be applied to control/datafields having various names, which include control information in awireless communication system transferring user data.

In addition, the HE PPDU of FIG. 2 is an example of a PPDU for multipleusers. The HE-SIG-B may be included only when the PPDU is for multipleusers. The HE SIG-B may be omitted in a PPDU for a single user.

As illustrated, the HE-PPDU for multiple users (MUs) may include variousfields such as legacy-short training field (L-STF), legacy-long trainingfield (L-LTF), legacy-signal (L-SIG), high efficiency-signal A (HE-SIGA), high efficiency-signal-B (HE-SIG B), high efficiency-short trainingfield (HE-STF), high efficiency-long training field (HE-LTF), data field(alternatively, a MAC payload), and packet extension (PE). Each of thefields may be transmitted during an illustrated time period (that is, 4or 8 μs).

The PPDU used in the IEEE standard is mainly described as a PPDUstructure transmitted with a channel bandwidth of 20 MHz. The PPDUstructure transmitted with a bandwidth (e.g., 40 MHz and 80 MHz) widerthan the channel bandwidth of 20 MHz may be a structure in which linearscaling is applied to the PPDU structure used in the channel bandwidthof 20 MHz.

The PPDU structure used in the IEEE standard may be generated based on64 Fast Fourier Transforms (FTFs), and a cyclic prefix portion (CPportion) may be ¼. In this case, a length of an effective symbolinterval (or FFT interval) may be 3.2 us, a CP length may be 0.8 us, andsymbol duration may be 4 us (3.2 us+0.8 us) that adds the effectivesymbol interval and the CP length.

FIG. 3 is a conceptual view illustrating an authentication andassociation procedure after scanning of an AP and an STA.

Referring to FIG. 3, a non-AP STA may perform the authentication andassociation procedure with respect to one AP among a plurality of APswhich have completed a scanning procedure through passive/activescanning. For example, the authentication and association procedure maybe performed through 2-way handshaking.

FIG. 3(A) is a conceptual view illustrating an authentication andassociation procedure after passive scanning, and FIG. 3(B) is aconceptual view illustrating an authentication and association procedureafter active scanning.

The authentication and association procedure may be performed regardlessof whether the active scanning or the passive scanning is used. Forexample, APs 300 and 350 exchange an authentication request frame 310,an authentication response frame 320, an association request frame 330,and an association response frame 340 with the non-AP STAs 305 and 355to perform the authentication and association procedure.

More specifically, the authentication procedure may be performed bytransmitting the authentication request frame 310 from the non-AP STAs305 and 355 to the APs 300 and 350. The APs 300 and 350 may transmit theauthentication response frame 320 to the non-AP STAs 305 and 355 inresponse to the authentication request frame 310. An authenticationframe format is disclosed in IEEE 802.11 8.3.3.11.

More specifically, the association procedure may be performed when thenon-AP STAs 305 and 355 transmit the association request frame 330 tothe APs 300 and 305. The APs 300 and 350 may transmit the associationresponse frame 340 to the non-AP STAs 305 and 355 in response to theassociation request frame 330.

The association request frame 330 may include information on capabilityof the non-AP STAs 305 and 355. The APs 300 and 350 may determinewhether the non-AP STAs 305 and 355 can be supported based on theinformation on capability of the non-AP STAs 305 and 355 and included inthe association request frame 330.

For example, if the support is available, the AP 300 and 350 maytransmit to the non-AP STAs 305 and 355 by allowing the associationresponse frame 340 to contain whether the association request frame 330is acceptable, its reason, and its supportable capability information.An association frame format is disclosed in IEEE 802.11 8.3.3.5/8.3.3.6.

When up to the association procedure mentioned in FIG. 3 is performed,normal data transmission and reception procedures may be performedbetween the AP and the STA.

FIG. 4 is an internal block diagram of a wireless terminal receiving awake-up packet.

Referring to FIG. 4, a WLAN system 400 according to the presentembodiment may include a first wireless terminal 410 and a secondwireless terminal 420.

The first wireless terminal 410 may include a main radio module 411related to main radio (e.g., 802.11 radio) and a WUR module 412including low-power wake-up radio (LP WUR). In the presentspecification, the main radio module may be referred to as a primarycomponent radio (hereinafter, PCR) module.

For example, the main radio module 411 may include a plurality ofcircuits supporting Wi-Fi, Bluetooth® radio (hereinafter, BT radio), andBluetooth® Low Energy radio (hereinafter, BLE radio).

In the present specification, the first wireless terminal 410 maycontrol the main radio module 411 in an awake state or a doze state.

For example, when the main radio module 411 is in the awake state, thefirst wireless terminal 410 is able to transmit an 802.11-based frame(e.g., 802.11-type PPDU) or receive an 802.11-based frame based on themain radio module 411. For example, the 802.11-based frame may be anon-HT PPDU of a 20 MHz band.

For another example, when the main radio module 411 is in the dozestate, the first wireless terminal 410 is not able to transmit the802.11-based frame (e.g., 802.11-type PPDU) or receive the 802.11-basedframe based on the main radio module 411.

That is, when the main radio module 411 is in the doze state (e.g., OFFstate), the first wireless terminal 400 is not able to receive a frame(e.g., 802.11-type PPDU) transmitted by the second wireless terminal 420(e.g., AP) until the WUR module 412 wakes up the main radio module 411to transition to the awake state according to a wake-up packet(hereinafter, WUP).

In the present specification, a WUR PPDU and a WUR frame can beunderstood as the same concept.

In the present specification, when a WUR MAC frame used to wake up theWUR module 412 in a turn-off state into a turn-on state is included in aWUR PPDU, the WUR PPDU may be referred to as a wake-up packet(hereinafter ‘WUP’).

In the present specification, a WUR frame of a WUR wake-up type forwaking up the WUR module 412 in a turn-off state into a turn-on statemay be referred to as a wake-up packet (WUP).

In the present specification, the first wireless terminal 410 cancontrol the WUR module 412 such that it switches to a turn-off state ora turn-on state.

For example, the first wireless terminal 410 including the WUR module412 in a turn-on state can receive (or demodulate) only a frame of aspecific type (i.e., WUR PPDU) transmitted by the second wirelessterminal 420 (for example, AP).

In this case, the frame of the specific type (i.e., WUR PPDU) may be aframe (e.g., wake-up packet) modulated according to an on-off keying(OOK) modulation method which will be described later with reference toFIG. 5.

For example, the first wireless terminal 410 including the WUR module412 in a turn-off state cannot receive (or demodulate) a frame of aspecific type (i.e., WUR PPDU) transmitted by the second wirelessterminal 420 (for example, AP).

In the present specification, the first wireless terminal 410 canoperate a main radio module (i.e., PCR module 411) and a WUR module 412.

For example, when the main radio module 411 is in a power save mode(hereinafter referred to as a PS mode)), the first wireless terminal 410can control the main radio module 411 such that it alternates between adoze state and an awake state according to communication environment.

For example, when the WUR module 412 is in a WUR mode, the firstwireless terminal 410 can control the WUR module 412 such that italternates between a turn-on state and a turn-off state according to astate of the main radio module 411 and a duty cycle schedule agreed inadvance for the WUR module.

Here, a wake-up packet modulated with OOK can be received based on theWUR module 412 in a turn-on state. In other words, the wake-up packetcannot be received based on the WUR module 412 in a turn-off state.

Specifically, when the main radio module 411 is in a doze state, thefirst wireless terminal 410 in a WUR mode controls the WUR module 412such that it is in a turn-on state for a duty cycle schedule agreedbetween the first wireless terminal 410 and the second wireless terminal420.

Further, when the main radio module 411 is in an awake-state, the firstwireless terminal in the WUR mode may control the WUR module 412 suchthat it is in a turn-off state.

That is, a wireless terminal in the WUR mode may be understood as awireless terminal having a negotiation status between an AP and a WURSTA, in which the WUR module alternates between a turn-of state and aturn-off state when the main radio module is in a doze state.

For example, the first wireless terminal 410 in the WUR mode can receivea wake-up packet (WUP) based on the WUR module 412 in a turn-on state.Further, when the WUR module 412 receives a WUP, the first wirelessterminal 410 in the WUR mode can control the WUR module 412 such that itwakes the main radio module 411 up.

In the present specification, the terms “awake state” and “turn-onstate” may be interchanged in order to indicate an ON state of aspecific module included in a wireless terminal. In the same context,the terms “doze state” and “turn-off state” may be interchanged in orderto indicate an OFF state of a specific module included in a wirelessterminal.

The first wireless terminal 410 according to the present embodiment canreceive a legacy frame (e.g., a PPDU based on 802.11) from anotherwireless terminal 420 (e.g., AP) based on the main radio module 411 orthe WUR module 412 in an awake state.

The WUR module 412 may be a receiver for switching the main radio module411 in a doze state to an awake state. That is, the WUR module 412 maynot include a transmitter.

The first wireless terminal 410 can operates the WUR module 412 in aturn-on state for a duration in which the main radio module 411 is in adoze state.

For example, when a WUP is received based on the WUR module 412 in aturn-on state, the first wireless terminal 410 can control the mainradio module 411 in a doze state such that it switches to an awakestate.

For reference, a low power wake-up receiver (LP WUR) included in the WURmodule 412 aims at target power consumption of less than 1 mW. Further,the LP WUR may use a narrow bandwidth of less than 5 MHz.

In addition, power consumption of the LP WUR may be less than 1 Mw.Further, a target transmission range of the LP WUR may be the same asthat of the legacy 802.11.

The second wireless terminal 420 according to the present embodiment cantransmit user data based on main radio (i.e., 802.11). The secondwireless terminal 420 can transmit a WUP for the WUR module 412.

In the present specification, when a wireless terminal includes the mainradio module and the WUR module, the wireless terminal may be referredto as a WUR STA.

FIG. 5 is a conceptual diagram illustrating a method in which a wirelessterminal receives a wake-up packet and a data packet.

Referring to FIG. 4 and FIG. 5, a WLAN system 500 according to thepresent embodiment may include a first wireless terminal 510corresponding to a receiving terminal and a second wireless terminal 520corresponding to a transmitting terminal.

A basic operation of the first wireless terminal 510 of FIG. 5 may beunderstood through a description of the first wireless terminal 410 ofFIG. 4. Similarly, a basic operation of the second wireless terminal 520of FIG. 5 may be understood through a description of the second wirelessterminal 420 of FIG. 4.

Referring to FIG. 5, the wake-up packet 521 may be received in a WURmodule 512 in a turn-on state (e.g., ON state).

In this case, the WUR module 512 may transfer a wake-up signal 523 to amain radio module 511 in a doze state (e.g., OFF state) in order toaccurately receive a data packet 522 to be received after the wake-uppacket 521.

For example, the wake-up signal 523 may be implemented based on aninternal primitive of the first wireless terminal 510.

For example, when the wake-up signal 523 is received in the main radiomodule 511 in the doze state (e.g., OFF state), the first wirelessterminal 510 may control the main radio module 511 to transition to theawake state (i.e., ON state).

For example, when the main radio module 511 transitions from the dozestate (e.g., OFF state) to the awake state (i.e., ON state), the firstwireless terminal 510 may activate all or some of a plurality ofcircuits (not shown) supporting Wi-Fi, BT radio, and BLE radio includedin the main radio module 511.

For another example, actual data included the wake-up packet 521 may bedirectly transferred to a memory block (not shown) of a receivingterminal even if the main radio module 511 is in the doze state (e.g.,OFF state).

For another example, when an IEEE 802.11 MAC frame is included in thewake-up packet 521, the receiving terminal may activate only a MACprocessor of the main radio module 511. That is, the receiving terminalmay maintain a PHY module of the main radio module 511 to be in aninactive state. The wake-up packet 521 of FIG. 5 will be described belowin greater detail with reference to the accompanying drawings.

The second wireless terminal 520 may be configured to transmit thewake-up packet 521 to the first wireless terminal 510.

Referring to FIG. 5, to indicates that an individually addressedframe(s) for the first wireless terminal 510 is available through themain radio module 511 (i.e., to indicate the presence of an individuallyaddressed frame(s) buffered by the second wireless terminal for thefirst wireless terminal), the second wireless terminal 520 can transmita wake-up packet 521 to the first wireless terminal 510 associated withthe second wireless terminal 520.

For example, the wake-up packet 521 may include information (e.g., a WURID) for identifying the first wireless terminal 510.

Alternatively, the wake-up packet 521 may include information (e.g., agroup ID) for identifying a group of a plurality of wireless terminalsincluding the first wireless terminal 510.

Alternatively, the wake-up packet 521 may include a plurality ofidentification information fields in a frame body field. Here, theplurality of identification information fields may include one foridentifying the first wireless terminal 510.

FIG. 6 illustrates an example of a WUR PPDU format.

Referring to FIGS. 1 to 6, a wake-up radio (WUR) PPDU 600 may include alegacy preamble 610 defined in IEEE 802.11. In the presentspecification, the legacy preamble 610 may be understood as a 20 MHznon-HT preamble.

In addition, the WUR PPDU 600 may include a BPSK-mark symbol field 615,a synchronization (hereinafter ‘Sync’) field 617 and a WUR-data field620 carrying a payload following the legacy preamble 610.

The WUR-data field 620 may be modulated using a simple modulation scheme(e.g., on-off keying (OOK)). That is, the WUR-data field 620 may includea payload for a reception terminal.

The legacy preamble 610 may be provided for coexistence with a legacySTA. An L-SIG field for protecting a packet may be used in the legacypreamble 610 for the coexistence.

For example, an 802.11 STA may detect a start portion of a packetthrough the L-STF field in the legacy preamble 610. The STA may detectan end portion of the 802.11 packet through the L-SIG field in thelegacy preamble 610.

The legacy preamble 610 may be understood as a field for a third partylegacy STA (STA not including LP-WUR). In other words, the legacypreamble 610 may not be decoded by the LP-WUR.

To reduce false alarm of an 802.11n terminal, a modulated BPSK-marksymbol field 615 may be added after L-SIG of FIG. 6.

For example, the BPSK-mark symbol field 615 may include a single symbolhaving a length of 4 μs modulated according to binary phase shift keying(BPSK). The BPSK-mark symbol field 615 may have a bandwidth of 20 MHzlike a legacy part.

The WUR PPDU 600 may include a narrow band portion corresponding to theSync field 617 and the WUR-data field 620 following the legacy preamble610 and the 20 MHz BPSK-mark symbol 615.

The Sync field 617 may be configured based on a plurality of predefinedsequences for discriminate from two data rates defined for the WUR-datafield 620.

The Sync field 617 may be modulated according to OOK. The duration ofthe Sync field 617 may be determined based on a data rate of theWUR-data field 620.

For example, when a data rate applied to the WUR-data field 620 is ahigh data rate (250 kbps), the duration of the Sync field 617 may be 64μs. When a data rate applied to the WUR-data field 620 is a low datarate (62.5 kbps), the duration of the Sync field 617 may be 128 μs.

That is, a WUR STA can ascertain whether a data rate applied to theWUR-data field 620 is a first data rate (62.5 kbps) for LDR or a seconddata rate (250 kbps) for HDR based on a result of detection of the Syncfield 617.

The WUR-data field 620 may be modulated according to OOK. The WUR-datafield 620 may be configured based on the first data rate (62.5 kbps) forLDR or the second data rate (250 kbps) for HDR

The WUR-data field 620 may be encoded based on Manchester code as shownin Table 1 and Table 2 below.

For example, when HDR is applied to the WUR-data field 620, an ON/OFFsymbol of the WUR-data field 620 according to OOK may be configured tohave a 2μ length. In this case, a mapping relationship between ON/OFFsymbols included in the WUR-data field 620 and an information bit to befinally acquired by a reception terminal may be as shown in Table 1below.

TABLE 1 Information bit Encoded bit 0 2μ ON + 2μ OFF 1 2μ OFF + 2μ ON

Referring to Table 1, an ON symbol having a 2μ length and an OFF symbolhaving a 2μ length included in the WUR-data field 620 can be interpretedas an information bit ‘0’. Further, an OFF symbol having a 2μ length andan ON symbol having a 2μ length included in the WUR-data field 620 canbe interpreted as an information bit ‘1’.

For example, when LDR is applied to the WUR-data field 620, ON/OFFsymbols of the WUR-data field 620 according to OOK may be configured tohave a 4μ length. In this case, a mapping relationship between ON/OFFsymbols included in the WUR-data field 620 and an information bit to befinally acquired by a reception terminal may be as shown in Table 2below.

TABLE 2 Information bit Encoded bit 0 4μ ON + 4μ OFF + 4μ ON + 4μ OFF 14μ OFF + 4μ ON + 4μ OFF + 4μ ON

Referring to Table 2, an ON symbol having a 4μ length and an OFF symbolhaving a 4μ length which are repeated twice and included in the WUR-datafield 620 can be interpreted as an information bit ‘0’. Further, an OFFsymbol having a 4μ length and an ON symbol having a 4μ length which arerepeated twice and included in the WUR-data field 620 can be interpretedas an information bit ‘1’.

Referring to FIGS. 1 to 6, the second wireless terminal (e.g., 520) maybe configured to generate and/or transmit the wake-up packet 521 or 600.The first wireless terminal (e.g., 510) may be configured to process thereceived wake-up packet 521.

FIG. 7 illustrates a signal waveform of a wake-up packet.

Referring to FIG. 7, a wake-up packet 700 may include a legacy preamble(802.11 preamble) 710 and payloads 722 and 724 modulated based on on-offkeying (OOK). That is, the wake-up packet WUP according to the presentembodiment may be understood in a form in which a legacy preamble and anew LP-WUR signal waveform coexist.

OOK may not be applied to the legacy preamble 710 of FIG. 7. Asdescribed above, the payloads 722 and 724 may be modulated according tothe OOK. However, the wake-up preamble 722 included in the payloads 722and 724 may be modulated according to another modulation scheme.

For example, it may be assumed that the legacy preamble 710 istransmitted based on a channel band of 20 MHz to which 64 FFTs areapplied. In this case, the payloads 722 and 724 may be transmitted basedon a channel band of about 4.06 MHz.

FIG. 8 is a diagram illustrating afrequency-division-multiplexing-access (FDMA) based WUR PPDU having a 40MHz channel bandwidth.

Referring to FIG. 8, a 40 MHz preamble may be acquired by duplicating a20 MHz preamble including L-STF, L-FTF, L-SIG and BPSK-mark fields.

For the FDMA based WUR PPDU having a 40 MHz channel bandwidth, differentSync fields may be applied to 20 MHz channels according to a data rateof the WUR-data field.

Referring to FIG. 8, in each 20 MHz subchannel having a duplicated 20MHz preamble, a single 4 MHz WUR signal located at the center of the 20MHz subchannel can be transmitted following the 20 MHz preamble.

In FDMA transmission, WUR PPDU transmission over respective 20 MHzsubchannels may be configured to have the same transmission durationusing a padding field.

Although FIG. 8 illustrates the FDMA based WUR PPDU having a 40 MHzchannel bandwidth, the present specification is not limited thereto.That is, the FDMA based WUR PPDU may be configured to have an 80 MHzchannel bandwidth.

FIG. 9 is a diagram illustrating a design process of a pulse accordingto OOK.

A wireless terminal according to the present embodiment may use anexisting orthogonal frequency-division multiplexing (OFDM) transmitterof 802.11 in order to generate pulses according to OOK. The existing802.11 OFDM transmitter may generate a 64-bit sequence by applying64-point IFFT.

Referring to FIG. 1 to FIG. 9, the wireless terminal according to thepresent embodiment may transmit a payload of a modulated wake-up packet(WUP) according to OOK. The payload (e.g., 620 of FIG. 6) according tothe present embodiment may be implemented based on an ON-signal and anOFF-signal.

The OOK may be applied for the ON-signal included in the payload (e.g.,620 of FIG. 6) of the WUP. In this case, the ON-signal may be a signalhaving an actual power value.

With reference to a frequency domain graph 920, an ON-signal included inthe payload (e.g., 620 of FIG. 6) may be obtained by performing IFFT forthe N2 number of subcarriers (N2 is a natural number) among the N1number of subcarriers (N1 is a natural number) corresponding to achannel band of the WUP. Further, a predetermined sequence may beapplied to the N2 number of subcarriers.

For example, a channel band of the wakeup packet WUP may be 20 MHz. TheN1 number of subcarriers may be 64 subcarriers, and the N2 number ofsubcarriers may be 13 consecutive subcarriers (921 in FIG. 9). Asubcarrier interval applied to the wakeup packet WUP may be 312.5 kHz.

The OOK may be applied for an OFF-signal included in the payload (e.g.,620 of FIG. 6) of the WUP. The OFF-signal may be a signal that does nothave an actual power value. That is, the OFF-signal may not beconsidered in a configuration of the WUP.

The ON-signal included in the payload (620 of FIG. 6) of the WUP may bedetermined (i.e., demodulated) to a 1-bit ON-signal (i.e., ‘1’) by theWUR module (e.g., 512 of FIG. 5). Similarly, the OFF-signal included inthe payload may be determined (i.e., demodulated) to a 1-bit OFF-signal(i.e., ‘0’) by the WUR module (e.g., 512 of FIG. 5).

A specific sequence may be preset for a subcarrier set 921 of FIG. 9. Inthis case, the preset sequence may be a 13-bit sequence. For example, acoefficient corresponding to the DC subcarrier in the 13-bit sequencemay be ‘0’, and the remaining coefficients may be set to ‘1’ or ‘−1’.

With reference to the frequency domain graph 920, the subcarrier set 921may correspond to a subcarrier whose subcarrier indices are ‘-6’ to‘+6’.

For example, a coefficient corresponding to a subcarrier whosesubcarrier indices are ‘−6’ to ‘−1’ in the 13-bit sequence may be set to‘1’ or ‘−1’. A coefficient corresponding to a subcarrier whosesubcarrier indices are ‘1’ to ‘6’ in the 13-bit sequence may be set to‘1’ or ‘−1’.

For example, a subcarrier whose subcarrier index is ‘0’ in the 13-bitsequence may be nulled. All coefficients of the remaining subcarriers(subcarrier indexes ‘−32’ to ‘−7’ and subcarrier indexes ‘+7’ to ‘+31’),except for the subcarrier set 921 may be set to ‘0’.

The subcarrier set 921 corresponding to consecutive 13 subcarriers maybe set to have a channel bandwidth of about 4.06 MHz. That is, power bysignals may be concentrated at 4.06 MHz in the 20 MHz band for thewake-up packet (WUP).

According to the present embodiment, when a pulse according to the OOKis used, power is concentrated in a specific band and thus there is anadvantage that a signal to noise ratio (SNR) may increase, and in anAC/DC converter of the receiver, there is an advantage that powerconsumption for conversion may be reduced. Because a sampling frequencyband is reduced to 4.06 MHz, power consumption by the wireless terminalmay be reduced.

An OFDM transmitter of 802.11 according to the present embodiment mayhave may perform IFFT (e.g., 64-point IFFT) for the N2 number (e.g.,consecutive 13) of subcarriers of the N1 number (e.g., 64) ofsubcarriers corresponding to a channel band (e.g., 20 MHz band) of awake-up packet.

In this case, a predetermined sequence may be applied to the N2 numberof subcarriers. Accordingly, one ON-signal may be generated in a timedomain. One bit information corresponding to one ON-signal may betransferred through one symbol.

For example, when a 64-point IFFT is performed, a symbol having a lengthof 3.2 us corresponding to a subcarrier set 921 may be generated.Further, when a cyclic prefix (CP, 0.8 us) is added to a symbol having alength of 3.2 us corresponding to the subcarrier set 921, one symbolhaving a total length of 4 us may be generated, as in the time domaingraph 910 of FIG. 9.

Further, the OFDM transmitter of 802.11 may not transmit an OFF-signal.

According to the present embodiment, a first wireless terminal (e.g.,510 of FIG. 5) including a WUR module (e.g., 512 of FIG. 5) maydemodulate a receiving packet based on an envelope detector thatextracts an envelope of a received signal.

For example, the WUR module (e.g., 512 of FIG. 5) according to thepresent embodiment may compare a power level of a received signalobtained through an envelope of the received signal with a predeterminedthreshold level.

If a power level of the received signal is higher than a thresholdlevel, the WUR module (e.g., 512 of FIG. 5) may determine the receivedsignal to a 1-bit ON-signal (i.e., ‘1’). If a power level of thereceived signal is lower than a threshold level, the WUR module (e.g.,512 of FIG. 5) may determine the received signal to a 1-bit OFF-signal(i.e., ‘0’).

Generalizing contents of FIG. 9, each signal having a length of K (e.g.,K is a natural number) in the 20 MHz band may be transmitted based onconsecutive K subcarriers of 64 subcarriers for the 20 MHz band. Forexample, K may correspond to the number of subcarriers used fortransmitting a signal. Further, K may correspond to a bandwidth of apulse according to the OOK.

All coefficients of the remaining subcarriers, except for K subcarriersamong 64 subcarriers may be set to ‘0’.

Specifically, for a one bit OFF-signal corresponding to ‘0’(hereinafter, information 0) and a one bit ON-signal corresponding to‘1’ (hereinafter, information 1), the same K subcarriers may be used.For example, the used index for the K subcarriers may be expressed as33-floor (K/2): 33+ceil (K/2)−1.

In this case, the information 1 and the information 0 may have thefollowing values.

-   -   Information 0=zeros (1, K)    -   Information 1=alpha*ones (1, K)

The alpha is a power normalization factor and may be, for example,1/sqrt (K).

FIG. 10 illustrates a basic operation for a WUR STA.

Referring to FIG. 10, an AP 1000 may correspond to the second wirelessterminal 520 of FIG. 5. A horizontal axis of the AP 1000 of FIG. 10 mayindicate a time ta. A vertical axis of the AP 1000 of FIG. 10 may berelated to presence of a packet (or frame) to be transmitted by the AP1000.

A WUR STA 1010 may correspond to the first wireless terminal 510 of FIG.5. The WUR STA 1010 may include a main radio module (or PCR #m) 1011 anda WUR module (or WUR #m) 1012. The main radio module 1011 of FIG. 10 maycorrespond to the main radio module 511 of FIG. 5.

Specifically, the main radio module 1011 may support both a receptionoperation for receiving an 802.11-based packet from the AP 1000 and atransmission operation for transmitting the 802.11-based packet to theAP 1000. For example, the 802.11-based packet may be a packet modulatedaccording to an OFDM scheme.

A horizontal axis of the main radio module 1011 may indicate a time tm.An arrow displayed at the lower end of the horizontal axis of the mainradio module 1011 may be related to a power state (e.g., ON state or OFFstate) of the main radio module 1011.

The WUR module 1012 in FIG. 10 may correspond to the WUR module 512 inFIG. 5. Specifically, the WUR module 1012 can support only an operationof receiving packets modulated with on-off keying (OOK) from the AP1000.

A horizontal axis of the WUR module 1012 may indicate a time tw. Anarrow indicated at the lower end of the horizontal axis of the WURmodule 1012 may be related to a power state (e.g., ON state or OFFstate) of the WUR module 1012.

The WUR STA 1010 in FIG. 10 may be understood as a wireless terminalassociated with the AP 1000 through an association procedure.

The WUR STA 1010 in FIG. 10 may be understood as a wireless terminaloperating in the PS mode. Accordingly, the WUR STA 1010 can control themain radio module 1011 such that it is in a doze state or an awakestate.

Further, the WUR STA 1010 may be understood as a wireless terminaloperating in the WUR mode. Accordingly, the WUR STA 1010 can control theWUR module 1012 such that it is in a turn-off state or a turn-on state.

Referring to FIG. 5 and FIG. 10, the AP 1000 of FIG. 10 may correspondto the second wireless terminal 520 of FIG. 5. A horizontal axis of theAP 1000 of FIG. 10 may represent a time ta. A vertical axis of the AP1000 of FIG. 10 may be related to presence of a packet (or frame) to betransmitted by the AP 1000.

The WUR STA 1010 may correspond to the first wireless terminal 510 ofFIG. 5. The WUR STA 1010 may include a main radio module (or PCR #m)1011 and a WUR module (or WUR #m) 1012. The main radio module 1011 ofFIG. 10 may correspond to the main radio module 511 of FIG. 5.

Specifically, the main radio module 1011 may support both a receptionoperation for receiving an 802.11-based packet from the AP 1000 and atransmission operation for transmitting an 802.11-based packet to the AP1000. For example, the 802.11-based packet may be a packet modulatedaccording to the OFDM scheme.

A horizontal axis of the main radio module 1011 may represent a time tm.An arrow displayed at the lower end of the horizontal axis of the mainradio module 1011 may be related to a power state (e.g., ON state or OFFstate) of the main radio module 1011.

A vertical axis of the main radio module 1011 may be related to presenceof a packet to be transmitted based on the main radio module 1011. A WURmodule 1012 of FIG. 10 may correspond to the WUR module 512 of FIG. 5.Specifically, the WUR module 1012 may support only a reception operationfor a packet modulated from the AP 1000 according to OOK.

A horizontal axis of the WUR module 1012 may represent a time tw.Further, an arrow displayed at the lower end of the horizontal axis ofthe WUR module 1012 may be related to a power state (e.g., ON state orOFF state) of the WUR module 1012.

In a wake-up period TW to T1 in FIG. 10, the WUR STA 1010 can controlthe main radio module 1011 such that it is in a doze state (i.e., OFFstate). Further, the WUR STA 1010 can control the WUR module 1012 suchthat it is in a turn-on state (i.e., ON state).

When a data packet for the WUR STA 1010 exists in the AP 1000, the AP1000 may transmit a wake-up packet (WUP) to the WUR STA 1010 in acontention-based manner.

In this case, the WUR STA 1010 may receive the WUP based on the WURmodule 1012 in a turn-on state (i.e., ON state). Herein, the WUP may beunderstood based on the description mentioned above with reference toFIG. 5 to FIG. 7.

In a first duration T1 to T2 of FIG. 10, a wake-up signal (e.g., 523 ofFIG. 5) for waking up the main radio module 511 according to the WUPreceived in the WUR module 1012 may be transferred to the main radiomodule 511.

In the present specification, a time required when the main radio module511 transitions from a doze state to an awake state according to thewake-up signal (e.g., 523 of FIG. 5) may be referred to as a turn-ondelay (hereinafter, TOD).

Referring to FIG. 10, the main radio module 511 may be in an awake stateafter a lapse of the turn-on delay (TOD).

For example, upon elapse of the TOD, the WUR STA 1010 may control themain radio module 1010 to be in the awake state (e.g., ON state). Forexample, upon elapse of a wake-up duration TW to T1, the WUR STA 1010may control the WUR module 1012 to be in the turn-on state (i.e., OFFstate).

Subsequently, the WUR STA 1010 may transmit a power save poll(hereinafter, PS-poll) to the AP 1000 based on the main radio module1011 in the awake state (i.e., ON state).

Here, a PS-poll frame may be a frame for indicating that the WUR STA1010 can receive a data packet for the WUR STA 1010 present within theAP 1000 based on the main radio module 1011. Further, the PS-poll framemay be a frame transmitted based on contention with another wirelessterminal (not shown).

Subsequently, the AP 1000 may transmit a first ACK frame ACK #1 to theWUR STA 1010 in response to a PS-poll frame.

Subsequently, the AP 1000 may transmit a data packet for the WUR STA1010 to the WUR STA 1010. In this case, the data packet for the WUR STA1010 may be received based on the main radio module 1011 in an awakestate (i.e., ON state).

Subsequently, the WUR STA 1010 may transmit a second ACK frame ACK #2for notification of successful reception of the data packet for the WURSTA 1010 to the AP 1000.

FIG. 11 is a diagram illustrating a MAC frame structure for a WUR frameaccording to an embodiment.

Referring to FIGS. 1 to 11, a WUR-data field (e.g., 620 of FIG. 6)included in a WUR PPDU according to an embodiment may conform to a MACframe structure 1100 of FIG. 11.

The MAC frame structure 1100 for the WUR frame may include a pluralityof fields 1110 to 1150.

The frame control field 1110 is configured based on 8-bit informationB0-B7 and will be described in more detail later with reference to FIG.12.

The ID field 1120 may be configured based on 12-bit information B8-B19.For example, when a wake-up packet is individually addressed,identification information fields (WUR identifier, ‘WUR ID’ hereinafter)for a single wireless terminal that receives a unicast wake-up packetcan be set to the ID field 1120.

Specifically, a WUR ID included in a unicast wake-up packet can be usedto identify a WUR STA intended for immediate response.

Alternatively, when a wake-up packet is group addressed, a group ID(hereinafter GID) for a plurality of wireless terminals receiving amulticast wake-up packet can be set to the ID field 1120.

Further, when a wake-up packet is broadcast addressed, an identificationinformation field (transmitter ID, hereinafter TXID) of a wirelessterminal transmitting a broadcast wake-up packet can be set to the IDfield 1120.

Alternatively, ‘0’ may be set to the ID field 1120 in order to signalinclusion of a plurality of WUR IDs in a frame body field (i.e., 1140 ofFIG. 11) of a wake-up packet.

The type dependent control field 1130 may be represented by 12-bitinformation B20-B31. For example, the type dependent control field 1130may include information related to BSS update.

The frame body field 1140 may have a variable length. The frame bodyfield 1140 may include WUR IDs for a plurality of wireless terminals.

For example, a WUR frame having a fixed length may not include the framebody field 1140. Alternatively, a WUR frame having a variable length mayinclude the frame body field 1140.

In the present specification, a WUR frame having a fixed length may bereferred to as a fixed-length (FL) WUR frame. For example, the FL WURframe may not include the frame body field.

A WUR frame having a variable length may be referred to as avariable-length (VL) WUR frame. For example, the VL WUR frame mayinclude a variable-length frame body field.

The frame check sequence (FCS) field 1150 may include 16-bit CRCinformation.

FIG. 12 is a diagram illustrating a structure of a frame control fieldof a WUR frame according to an embodiment.

Referring to FIG. 12, the frame control field 1200 (e.g., 1110 of FIG.11) of the WUR frame according to an embodiment may include a pluralityof fields 1210 to 1250.

The type field 1210 may include 3-bit information as shown in Table 3below.

TABLE 3 Type Type description 0 WUR Beacon 1 WUR Wake-up 2 WUR VendorSpecific 3 WUR discovery 4-7 Reserved

For example, referring to Table 3, when a WUR frame type is a WUR beaconframe, the WUR beacon frame can be understood as an FL WUR frame thatdoes not include the frame body field (e.g., 1140 of FIG. 11).

For example, a WUR wake-up frame (i.e., wake-up packet) including asingle WUR ID, a WUR wake-up frame (i.e., wake-up packet) including asingle GID, and a WUR wake-up frame (i.e., wake-up packet) including aTXID can be understood as FL WUR frames including no frame body field(e.g., 1140 of FIG. 11).

However, a WUR wake-up frame (i.e., wake-up packet) including aplurality of WUR IDs can be understood as a VL WUR frame including theframe body field (e.g., 1140 of FIG. 11).

The VL WUR frame includes information related to the length of the framebody field (e.g., 1140 of FIG. 11), whereas the FL WUR frame does notinclude information related to the length of the frame body field (e.g.,1140 of FIG. 11).

According to conventional technology, the type field 1210 is allocatedonly one value for a WUR wake-up frame (i.e., wake-up packet), andinformation for differentiating the VL WUR frame from the FL WUR frameis not additionally included in the frame control field 1200 of the WURframe.

Hereinafter, the present specification discloses a method for signalinginformation for differentiating the VL WUR frame from the FL WUR frameusing some bits of the frame control field of the WUR frame.

According to an embodiment, the length present field 1220 may includeinformation related to whether the subsequent field 1230 includes alength subfield for a VL WUR frame. For example, the length presentfield 1220 may be configured to have a 1-bit length.

The length/mist field 1230 may include a length subfield based on thelength present field 1220.

For example, when the length present field 1220 is set to a first valuefor a VL WUR frame, the length/mist field 1230 may include informationrelated to the length of the frame body field (e.g., 1140 of FIG. 11).

Alternatively, when the length present field 1220 is set to a secondvalue for an FL WUR frame, the length/mist field 1230 may be reserved.Alternatively, when the length present field 1220 is set to the secondvalue, the length/mist field 1230 may include other information.

The protected field 1240 may include information for indicating whetherinformation transmitted through the wake-up packet is processed by amessage integrity check (MIC) algorithm.

The positions of the plurality of fields illustrated in FIG. 12 areexemplary and the present specification is not limited thereto. Forexample, the position of the length present field 1220 may beinterchanged with the position of the protected field 1240.

FIG. 13 is a flowchart illustrating a method for communicating in awireless LAN system according to an exemplary embodiment from an APperspective.

Referring to FIGS. 1 to 13, a first wireless terminal of FIG. 13 may beunderstood as an access point (AP) and that a plurality of secondwireless terminals of FIG. 13 may be understood as some (or all) of aplurality of stations (STAs) associated with the first wireless terminalwhich is the first wireless terminal.

In addition, each of the plurality of second radio terminals mentionedin FIG. 13 (e.g., 510 in FIG. 5) may include a primary connectivityradio (PCR) module (e.g., 511 in FIG. 5) and a Wake-Up Radio (WUR)module (e.g., 512 of FIG. 5) for receiving a wake-up packet modulated byan OOK technique.

In addition, each of the plurality of second wireless terminals referredto in FIG. 13 (e.g., 510 of FIG. 5) may control its own WUR module to bein a turn-on state in order to receive a wake-up packet which is to bereceived from the first wireless terminal.

In operation S1310, the first wireless terminal may generate a wake-uppacket modulated by an On-Off Keying (OOK) technique.

For example, the wake-up packet may include a plurality ofidentification information fields for the plurality of second wirelessterminals.

For example, each of the plurality of identification information fieldsmay be generated based on a bit length unit having a fixed size. In thiscase, the bit length unit having the fixed size may be set to 12 bits.

Specifically, a plurality of unicast identification information fields(e.g., WUR IDs) for individually identifying the plurality of secondwireless terminals may be a frame body field (e.g., 1140 of FIG. 11) ina wake-up packet.

In operation S1320, the first wireless terminal may transmit the wake-uppacket to the plurality of second wireless terminals.

For example, the PCR module (e.g., 511 of FIG. 5) included in each ofthe plurality of second radio terminals (e.g., 510 of FIG. 5) may becontrolled to remain in an awake state in order to perform 20 MHzband-based communication with the first wireless terminal (e.g., 520 ofFIG. 5) according to a plurality of identification information fields.

FIG. 14 is a flowchart illustrating a method for communicating in a WLANsystem according to an exemplary embodiment from a STA perspective.

referring to FIGS. 1 to 14, a first wireless terminal of FIG. 14 may beunderstood as an access point (AP) and that a plurality of secondwireless terminals may be understood as some (or all) of a plurality ofstations (STAs) associated with the first wireless terminal which is theAP. In addition, a communication terminal mentioned in FIG. 14 may beunderstood as any one of a plurality of STAs combined with a firstwireless terminal that is an AP.

In addition, each of the plurality of second wireless terminalsmentioned in FIG. 14 (e.g., 510 of FIG. 5) may receive a primaryconnectivity radio (PCR) module (e.g., 511 of FIG. 5) and a Wake-UpRadio (WUR) module (e.g., 512 of FIG. 5) for receiving a wake-up packetmodulated by an OOK technique.

In addition, each of the plurality of second wireless terminalsmentioned in FIG. 14 (e.g., 510 of FIG. 5) may control its own WURmodule (e.g., 512 of FIG. 5) to be in a turn-on state in order toreceive a wake-up packet which is to be received from the first wirelessterminal (e.g., 520 of FIG. 5).

In addition, the communication terminal referred to in FIG. 14 (e.g.,510 of FIG. 5) may include the PCR module (e.g., 511 of FIG. 5) and theWUR module (e.g., 512 of FIG. 5) for receiving a wake-up packetmodulated by the OOK technique.

In operation S1410, the communication terminal may receive a wake-uppacket modulated by an On-Off keying (OOK) technique from the firstwireless terminal.

For example, the wake-up packet may include a plurality ofidentification information fields for the plurality of second wirelessterminals.

For example, each of the plurality of identification information fieldsmay be generated based on a bit length unit having a fixed size. In thiscase, the bit length unit having the fixed size may be set to 12 bits.

Specifically, a plurality of unicast identification information fields(e.g., WUR IDs) for individually identifying the plurality of secondwireless terminals may be included in a frame body field (e.g., 1140 ofFIG. 11) in the wake-up packet.

For example, the communication terminal of FIG. 14 (e.g., 510 of FIG. 5)may receive a plurality of identification information fields included inthe wake-up packet based on its own WUR module (e.g., 512 of FIG. 5) inthe turn-on state.

In operation S1420, the communication terminal may determine, based on abit length unit, whether or not its own preset identificationinformation field (that is, WUR ID) is included in the plurality ofidentification information fields (e.g., WUR IDs) acquired from thewake-up packet.

For example, if a frame body field (e.g., 1140 of FIG. 11) is includedin the received wakeup packet, the communication terminal in FIG. 14 mayscan the plurality of identification information fields (e.g., WUR IDs)based on a bit length unit having a fixed size.

In other words, the communication terminal of FIG. 14 may determine,based on a bit length unit having a fixed size, whether informationmatching its own identification information field (that is, WUR ID) isincluded in a plurality of identification information fields (e.g., WURIDs).

If it is determined that its own preset identification information fieldis not included in the plurality of identification information fields,the procedure is terminated. In this case, for a power saving operation,the communication terminal may control the PCR module to maintain a dozestate while maintaining only its own WUR module in the turn-on state.

If it is determined that its own preset identification information fieldis included in the plurality of identification information fields, theoperation S1430 may be performed.

In operation S1430, the communication terminal may control its own PCRmodule to be in an awake state in order to perform 20 MHz band-basedcommunication with the first wireless terminal which is the AP.

According to this embodiment, since whether or not its ownidentification information field is included in a wake-up packet isdetermined based on a bit length unit having a fixed size, complexity ofimplementing a low-power communication terminal including a WUR modulemay be relatively reduced.

FIGS. 15 to 21 illustrate a format structure of a VL WUR frame includinga plurality of identification information fields configured based on abit length unit having a variable length.

Referring to FIG. 15, information on a size (e.g., 6 bits) ofidentification information field (e.g., WUR ID which is hereinafterreferred to as “WID”) for a wireless terminal addressed by a wake-upframe may be included in an MAC header of a VL WUR frame 1500.

For example, five identification information fields (e.g., WIDs) eachhaving a size of 6 bits may be included in a frame body fieldimplemented with 4 bytes. In this case, the remaining 2 bits of theframe body field may be reserved or used for other purposes.

Referring to FIG. 16, information on a length of a frame body field maybe included in an MAC header of a VL WUR frame 1600. In this case,information on a size (WID size, 2 bits) of identification informationfield (that is, WID) for a wireless terminal may be included at thefront of the frame body field.

For example, when a 2 bits-based WID size indicates “6”, fiveidentification information fields (e.g., WIDs) each having a size of 6bits may be included in the frame body field of the VL WUR frame 1600.

Referring to FIG. 17, information on a length of a frame body field,information on a size (e.g., WID size) of identification informationfield (e.g., WID) for a wireless terminal, and information (e.g.,NumOfWID) on a number of identification information field (e.g., WID)included in the frame body field may be included in an MAC header of aVL WUR frame 1700.

For example, according to information (e.g., WID size, NumOfWID)included in the MAC header, four identification information fields(e.g., WID) each having a size of 6 bits may be included in the framebody field of the VL WUR frame 1700. The remaining 8 bits of the framebody field in FIG. 17 may be used for other purposes.

Referring to FIG. 18, FIG. 18 may be understood as a case where theremaining 8 bits of the frame body field of FIG. 17 are not used forother purposes.

For example, according to information (WID size, NumOfWID) included inan MAC header of a VL WUR frame 1800, four identification informationfields (e.g., WID) each having a size of 6 bits may be included in aframe body field of a VL WUR frame 1800.

Referring to FIG. 19, information on a length of a frame body field andinformation (e.g., WID size) on a size of identification informationfield (e.g., WID) for a wireless terminal may be included in the MACheader of the VL WUR frame 1800.

Information (e.g., NumOfWID) on a number of identification informationfield (that is, WID) included in a frame body field implemented with 2bits may be included at the front of the frame body field of the VL WURframe 1800.

For example, according to information (that is, WID size) included in anMAC header of a VL WUR frame 1900 and information (e.g., NumOfWID)included in the frame body field, five identification information fields(that is, WID) each having a size of 6 bits may be included in the framebody field of the VL WUR frame 1900.

Referring to FIG. 20, information on a length of a frame body field maybe included in an MAC header of a VL WUR frame 2000.

In addition, information (that is, WID size) on a size of identificationinformation field (that is, WID) for a wireless terminal and information(that is, NumOfWID) on a number of identification information fields(that is, WID) included in the frame body field may be included in theframe body field of the VL WUR frame 2000.

For example, according to information included in the MAC header of theVL WUR frame 1900 and information included in the frame body field (thatis, WID size, NumOfWID), four identification information fields (thatis, WID) each having a size of 6 bits may be included in the frame bodyfield of the VL WUR frame 1900.

Referring to FIG. 21, information on a length of a frame body field andinformation (e.g., NumOfWID) on a number of identification informationfield (e.g., WID) included in the frame body field may be included in anMAC header of a VL WUR frame 2100.

In addition, information (e.g., WID size) on a size of identificationinformation field (e.g., WID) for a wireless terminal may be included inthe frame body field of the VL WUR frame 2100.

For example, according to information (e.g., NumOfWID) included in theMAC header of the VL WUR frame 2100 and information (e.g., WID size)included in the frame body field, four identification information fields(e.g., WID) each having a size of 6 bits may be included in the framebody field of the VL WUR frame 2100.

FIG. 22 is a diagram of a method of determining information on a size ofidentification information field for a wireless terminal according toanother embodiment.

Referring to FIG. 22, a size of identification information field for awireless terminal may be signaled in advance to an STA during frametransmission and reception (e.g., WUR parameter negotiation exchangeprocedure) with respect to an AP based on a PCR module for 20 MHz bandof the STA.

Specifically, the WUR parameter negotiation exchange procedure isunderstood as a concept including exchange of Enter WUR Mode SignalingRequest/Response frame, exchange of Enter WUR Mode SuspendRequest/Response frame, exchange of WUR Action frame, or exchange ofAssociation Request/Response frame.

For example, the STA in a WUR mode may, when receiving a WUR frame, maydetermine a size (e.g., WID Size) of identification information fieldincluded in the frame body field included in the WUR frame based oninformation previously received from the AP.

For example, through the PCR module of FIG. 22 (or WLAN), the AP maytransmit a WUR Action frame (in the case of FIG. 22, Enter WUR ModeSignaling Response frame) to the STA.

For example, the WUR Action frame may include WID Size (N) information.Here, a value of N may be a natural number greater than 1 and less thanor equal to 12.

FIGS. 23 and 24 illustrate a format structure of a VL WUR framedepending on a transmission rate according to yet another embodiment ofthe present disclosure.

Referring to FIG. 23, when an LDR for a VL WUR frame 2300 is 62.5 kbps,identification information field (e.g., WID) for a wireless terminal maybe set to 6 bits (or 8 bits).

For example, the VL WUR frame 2300 may include five identificationinformation fields (e.g., WIDs) each having a size of 6 bits.

Referring to FIG. 24, when an HDR for a VL WUR frame 2400 is 250 kbps,an identification information field (e.g., WID) for a wireless terminalmay be set to 12 bits (or 10 bits).

For example, the VL WUR frame 2400 may include three identificationinformation fields (that is, WIDs) each having a size of 12 bits.

FIG. 25 is a block diagram illustrating a wireless device to which thepresent embodiment is applicable.

Referring to FIG. 25, a wireless device is an STA capable ofimplementing the above-described embodiment and may operate as an AP ora non-AP STA. In addition, the wireless device may correspond to theabove-described user or a transmission device that transmits a signal tothe user.

A wireless device of FIG. 25 includes a processor 2510, a memory 2520,and a transceiver 2530, as illustrated. Each of the processor 2510, thememory 2520, and the transceiver 2530 may be implemented as separatechips, at least two or more blocks/functions may be implemented usingone chip.

The transceiver 2530 is a device including a transmitter and a receiver,and when a specific operation is performed, only one of the transmitterand receiver or both of the transmitter and receiver operations mayoperate. The transceiver 2530 may include one or more antennas thattransmit and/or receive wireless signals. In addition, the transceiver2530 may include an amplifier for amplifying a received signal and/or atransmitted signal and a band pass filter for transmission on a specificfrequency band.

The processor 2510 may implement functions, processes, and/or methodsproposed in this specification. For example, the processor 2510 mayperform an operation according to the present embodiment describedabove. That is, the processor 2510 may perform the operations disclosedin the embodiments of FIGS. 1 to 24.

The processor 2510 may include an application-specific integratedcircuit (ASIC), a separate chipset, a logic circuit, a data processingunit, and/or a converter for mutually converting a baseband signal and aradio signal. The memory 2520 may include a read-only memory (ROM), arandom access memory (RAM), a flash memory, a memory card, a storagemedium, and/or other equivalent storage devices.

Although embodiments of the present disclosure have been described indetail in the present specification, various modifications are possiblewithout departing from the scope of the present specification.Therefore, the scope of the present specification should not beconstrued as being limited to the aforementioned embodiments, but shouldbe defined by not only claims of the specification described below butalso equivalents to the claims.

1. A method for communicating in a wireless Local Area Network (LAN)system performed by a first wireless terminal, the method comprising:generating a wake-up packet modulated by an On-Off Keying (OOK)technique wherein the wake-up packet comprises a plurality ofidentification information fields for a plurality of second wirelessterminals, each of the plurality of identification information fields isgenerated based on a bit length unit having a fixed size, and the bitlength unit having the fixed size is set to 12 bits; and transmittingthe wakeup packet to the plurality of second wireless terminals.
 2. Themethod of claim 1, wherein each of the plurality of second wirelessterminals comprises a primary connectivity radio (PCR) module and awake-up radio (WUR) module for receiving the wake-up packet modulated bythe OOK technique.
 3. The method of claim 2, wherein the WUR moduleincluded in each of the plurality of second wireless terminals toreceive the wake-up packet is controlled to be in a turn-on state. 4.The method of claim 2, wherein the PCR module included in each of theplurality of second wireless terminals is controlled to be in an awakestate to perform 20 MHz band-based communication with the first wirelessterminal according to the plurality of identification information.
 5. Amethod for communicating in a wireless Local Area Network (LAN) system,the method performed by a communication terminal that comprises aprimary connectivity radio (PCR) module and a wake-up radio (WUR) modulefor receiving a wake-up packet modulated by an On-Off Keying (OOK)technique and the method comprising: receiving the wake-up packet from afirst wireless terminal, wherein the wake-up packet comprises aplurality of identification information fields for a plurality of secondwireless terminals, each of the plurality of identification informationfields is generated based on a bit length unit having a fixed size, andthe bit length unit having the fixed size is set to 12 bits; anddetermining, based on the bit length unit, whether a presetidentification information field for the communication terminal isincluded in the plurality of identification information fields; and whenit is determined that preset identification information fields isincluded in the plurality of identification information, controlling thePCR module to be in an awake state to perform 20 MHz band-basedcommunication with the first wireless terminal.
 6. The method of claim5, wherein the plurality of identification information fields isacquired based on a WUR module included in the communication terminal,and the WUR module is in a turn-on state.
 7. A first wireless terminalperforming a method for communicating in a wireless Local Area Network(LAN) system, the first wireless terminal comprising: a transceiverconfigured to transmit and receive wireless signals; and a processorconnected to the transceiver, wherein the processor is configured to:generate a wake-up packet modulated by an On-Off Keying (OOK) technique,wherein the wake-up packet comprises a plurality of identificationinformation fields for a plurality of second wireless terminals, each ofthe plurality of identification information fields is generated based ona bit length unit having a fixed size, and the bit length unit havingthe fixed size is set to 12 bits; and transmit the wake-up packet to theplurality of second wireless terminals.
 8. The wireless terminal ofclaim 7, wherein each of the plurality of second wireless terminalscomprises a primary connectivity radio (PCR) module and a wake-up radio(WUR) module for receiving the wake-up packet modulated by the OOKtechnique.
 9. The wireless terminal of claim 8, wherein the WUR moduleincluded in each of the plurality of second wireless terminals toreceive the wake-up packet is controlled to be in a turn-on state.